1. Field of the Invention
The invention relates to a free wheel hub for a four wheel drive automobile, and in particular the electrical connections from the battery to an actuator and a sensor positioned in the free wheel hub mechanism.
2. Description of the Related Art
A free wheel hub system for a four wheel drive automobile is known which includes a sensor indicating the operating condition of the free wheel hub to the driver when the free wheel hub operates automatically in the four wheel driving condition, or indicates actuation of an electric motor which changes the four wheel driving condition to the two wheel driving condition in the axle hub or vice versa.
The prior art shown in FIG. 10 shows a free wheel hub system equipped by a switch sensor 2 so as to indicate the operating condition of the free wheel hub to the driver. When the free wheel hub system changes to the four wheel driving condition. The four wheel drive is actuated by the operation of a hub ring 5 rotating with a drive shaft 3 and an inner hub 4, and roller cage 7 rotates to the left with a roller 6 and contacts a movable part 2a of the switch sensor 2 fixed on the outer side of a spindle 1. The roller 6 engages a clutch housing 8 and the inner hub 4. Thereby, the switch sensor 2 is switched to the ON position and the transmission of a driving force from the drive shaft 3 to the wheel is indicated. An indicator (not shown in FIG. 10) mounted in a dashboard is connected to the switch sensor 2 through electrical wiring 9 which is wired through an opening 1A formed in the spindle 1, or as shown in FIG. 11, along a groove 1B formed on the inner face of the spindle 1.
The foregoing free wheel hub system has a drawback in that the spindle 1 has a reduced load, caused by the forming of the opening 1A or the groove 1B. Therefore, the transferable torque load of such a free wheel hub system is limited. Further, it is not possible to design the opening 1A or the groove 1B to an increased extent, therefore, the diameter of the electrical wiring 9 is limited. The wiring 9 can be broken during assembly or by the vibrations received from the wheel, thereby making the free wheel hub system unreliable. Further, a great deal of care is needed to mount the drive shaft 3 to the spindle 1 without breaking the wiring 9 which leads to extended assembly time.